Respiratory masks used in the treatment of SDB may comprise either a nasal mask, designed to fit over a patient's nose, or a full face mask designed to fit over the nose and mouth of the patient. Air or other breathable gas is supplied by a blower and passed along a flexible conduit to the mask.
The mask generally comprises a relatively rigid shell, termed a frame, which defines a rearwardly opening cavity covering the patient's nose and/or mouth and a soft portion, termed a cushion, which spaces the frame away from the face for comfortable contact.
The masks are typically held in place using headgear, the mask and headgear being joined using some form of connector.
One known example is the Mirage® Mask (ResMed Limited), shown in FIG. 1. In this case, the headgear 100 is constructed from fabric and includes a rear portion, which engages the region near the occiput of the patient, and four straps 110 which are secured to a forehead support 120 (2 straps) and nasal mask frame 130 (2 straps). The straps include hook and loop material, such as Velcro™ on one side. The mask frame and forehead supports include loops 140 through which a strap can pass. In order to secure the mask in place on a patient's head, the four straps are passed through the four corresponding loops and held in place at an appropriate length by the hook and loop material. The patient can adjust the length of the material in order to secure a good fit of the mask. In some cases, it can require considerable adjustment to find the optimal length of straps which is required. A difficulty with this connector is that if the patient removes the mask by loosening the straps, they will lose what may have been a good fit of the mask the next time it is being used. In this case they will need to repeat the adjustment step.
Another known manner of connecting the mask and headgear is shown in FIGS. 2a, 2b and 2c. In this headgear, a short strap length 200 is secured to one side of the mask, with a two-part, press-release connector 210, 220 attaching this to the strap 250 of the headgear. One disadvantage of the approach of using this arrangement is that the connector may be difficult to release because the connector is free to move relative to the mask frame. A further disadvantage of this arrangement is that the connector may be in contact with the patient's face which may lead to discomfort in use, particularly if they sleep on their side.
More detailed views of this prior art connector are shown in FIGS. 2b and 2c. Each part of the connector includes a bar 230, 240 behind which a respective one of the straps 200, 250 may be passed. The male portion 220 of the connector includes a resilient cantilever 260 which is captured behind a bar 270 on the female portion 210. The cantilever is depressed to engage and disengage the connector. A further disadvantage of this particular connector, best seen in FIG. 2b, is that it may be awkward to disengage the connector because of the close positioning of the bar 270 to the cantilever 260.
Another known mask and headgear connector is shown in FIG. 3a to FIG. 3d. This comprises a flexible part 310 positioned on the outer surface of a flexible mask frame 300 and a rigid part 320 formed generally as a D-ring with a loop to which the headgear strap is attached. The flexible part consists of a base 330 supporting an upper portion 340 (best illustrated in FIG. 3a) which overhangs the base portion 330 and has a narrow central region 350. In order to engage and disengage the connector, the flexible part 310 must be deformed whilst the D-ring of the rigid part is pushed over the upper portion 340 to engage below the overhanging ledge. This arrangement is awkward to engage and disengage and typically requires two hands.
Another known mask and headgear connector consists of hooks on the end of the headgear straps and corresponding holes in the mask frame. To engage the mask and headgear connector, the hook is passed through one of the corresponding holes on the headgear. This arrangement is also awkward to engage and disengage and typically requires two hands. Also, it is possible for the hooks to disengage during sleep as there is no locking means for the connection.
There is a need for a connector arrangement which is simple and quick to operate.